<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>样式覆盖测试</title>
    <style>
      .c1{
        color:red !important;
        border:1px solid red ;

      }
      .c2{
        font-size: 28px;
        color: green;
      }
    </style>
</head>
<body>

  <div class="c1 c2 c1">中国联通</div>

</body>
</html>